This invention relates to an electrical circuit arrangement for igniting and feeding a gas and/or vapour discharge tube provided with two preheatable electrodes. The circuit includes two input terminals adapted to be connected to an alternating voltage supply source. In the connected condition of the discharge tube, one input terminal is connected via at least one inductive stabilization ballast to a first end of one of the preheatable electrodes and the second input terminal is connected to a first end of the second preheatable electrode. The first ends of the two electrodes are interconnected through a first capacitor and the ends of the two electrodes remote from the supply are interconnected through a second capacitor. The invention further relates to a combination of such an electrical circuit arrangement with an interposed DC/AC converter.
A known electrical circuit arrangement of the kind mentioned is described, for example, in Australian Patent No. 138,729. A disadvantage of this known circuit arrangement is that--in order to ensure that the lamp ignites readily at preheated electrodes--the capacitance of the second capacitor, and hence the volume of this second capacitor, should be comparatively large. In fact, the larger will be this capacitance, the larger the electrode preheating current, that is to say the sooner these electrodes will reach the emission temperature and hence the sooner the lamp ignites. A comparatively large second capacitor also has the disadvantage that the freedom of choice of the remaining circuit elements needed for operating the discharge tube is reduced.